Crankshaft rolling apparatus

ABSTRACT

A crankshaft blank, having a cylindrical surface to be rolled and at opposite axial ends of which there are crankshaft fillets, is held between two lever arms under pressure. The lever arms are associated with a pair of master crankshafts in such a manner that, when the master crankshafts are rotated, the lever arms move correspondingly and in unison therewith. A tool unit is provided on one of the arms and includes a tool roller having axially arrayed portions of mutually opposite conicity, or two separate rollers which are conical in mutually opposite direction. The single roll or the two rollers engage the cylindrical surface of the blank intermediate the crankshaft fillets having at their respective axial end faces radii of curvature merging into their circumferential surfaces; these radii of curvature are smaller by between substantially 20-30 percent than the radius of the crankshaft fillets on the blank and thus also of the crankshaft fillets on the master crankshaft which are identical with the crankshaft fillets on the blank.

United States Patent 1 1 1 397351629 Naumann 1 1 May 29, 1973 CRANKSHAFT ROLLING APPARATUS 1,070,955 12/1959 Germany ..29/6

lnventor: Hans-Joachim Naumann, Wassenberg, Germany Wilhelm HegenscheidtKommanditgesellschaft, Erkelenz, Germany Filed: Feb. 7, 1972 Appl. No.:223,892

Assignee:

Foreign Application Priority Data References Cited UNITED STATES PATENTSGreatBritain ..72/l10 Primary ExaminerLowell A. Larson Attorney-MichaelS. Striker [57] ABSTRACT A crankshaft blank, having a cylindricalsurface to be rolled and at opposite axial ends of which there arecrankshaft fillets, is held between two lever arms under pressure. Thelever arms are associated with a pair of master crankshafts in such amanner that, when the master crankshafts are rotated, the lever armsmove correspondingly and in unison therewith. A tool unit is provided onone of the arms and includes a tool roller having axially arrayedportions of mutually opposite conicity, or two separate rollers whichare conical in mutually opposite direction. The single roll or the tworollers engage the cylindrical surface of the blank intermediate thecrankshaft fillets having at their respective axial end faces radii ofcutvature merging into their circumferential surfaces; these radii ofcurvature are smaller by between substantially 20-30 percent than theradius of the crankshaft fillets on the blank and thus also of thecrankshaft fillets on the master crankshaft which are identical with thecrankshaft fillets on the blank.

10 Claims, 6 Drawing Figures PATENILL M29 1915.

SHEET 1 [1r 4 PATENTEW- 3.735.620

SHEET 2 (1F 4 PAH-INTEL HAY 2 91973 SHEET 3 BF 4 WWW 1 CRANKSHAFTROLLING APPARATUS BACKGROUND OF THE INVENTION The present inventionrelates to the rolling of a crankshaft and more particularly to acrankshaft rolling apparatus.

It is already well known to subject crankshafts to a rolling operation,in order to advantageously influence the material of the crankshaft andimprove the fatigue loss thereof. This type of rolling apparatus. isknown as a tangential fillet rolling apparatus and is employed forrolling the fillets on the. crankshaft, that is the curved transitionsbetween crankpin and crankshaft bearing surfaces. Generally speaking, aknown tangential fillet rolling, machine consists of a driving unit, twomaster crankshafts which drive lever arms but hold rolling tool:assemblies, a loading and an unloading device, and -such hydrauliccylindersand supply as are necessary to apply pressure to the toolingfor the cold rolling operation of the crankshaft blank which is heldbetween the lever arms. The latter are acted upon bythe hydrauliccylinders to put them through a moment of leverage and make it possibleto apply a high squeeze pressure to the rolling tool assemblies whichinclude actual rolling tools and back-up rollers. A crankshaft blank isloaded into the apparatus and thelever arms close the tooling aroundttheblank, whereupon the driving mechanism for the master crankshafts causesthe lever arms to reciprocate to thereby force the crankshaft blank.(the workpiece). to follow the same type of motion as it would wheninstalled in an engine assembly. The rolling tool assemblies are appliedagainst the surfaces on the crankshaft blank being worked, at apredetermined pressure to-thereby roll the surface. in uestion.

It is already known to utilize in the rolling toolassemblies'toolrollers of relatively small diameters which. are

supported by contact rollers of larger diameters, engag-- ing the latterat their circumference. The purpose of this arrangement is to be able touse tool rollers of small diameter in order to obtain high specificsurface pressures upon the workpiece at relatively 'lowtool pressures orsqueeze pressures. The tool rollers are used for rolling the filletswhereas the support rollers which support them are used to roll thecircumferential surface intermediate the axially spaced fillets becausethis circumferential cylindricalsurface may become slightly bowed inradially outwarddirection as a result of the pressures exerted upon thefillets. The purpose of the support rollers is thus two-fold, namely onthe one hand to support the tool rollers which act on the fillets and'on the other hand to attempt to either prevent or counteract (smoothout) this bowing effect of thecylindrical circumferential surface.

The tool rollers themselves are turnable about skew axes and the supportrollers are so arranged with respect to the tool rollers that the lattertend to center and maintain the tool carrier assembly against movementin a sense which would permit contact of the tool rollers with theradial surfaces into which the respective fillets merge, that'is thesurfaces which extend transversely of the longitudinal axes surroundedby the respective cylindrical surface. In some instances, andinparticular where crankshaft blanks (workpieces) of larger dimensionsare to be so processed, it is possible to omit the tangential rolling ofthe fillets because the large dimension of the crankshaft providessufficient material and fatigue life without rolling. However, with thistype of crankshaft a bearing seat is required having the maximumpossible supporting capability, a requirement which heretofore has beencapable of achievement only by lapping. In view of the fact that acrankshaft in a four-cylinder engine having three main bearings alreadyrequires seven bearing surfaces which must be lapped, and that lappingduring rotation of the crankshaft requires an additional axial swingmovement at each bearing surface with the crankpins moving not abouttheir axes, but in a circular orbit, it is clear that requirements forlapping the bearing seats on the crankpins are very expensive andcomplicated and that the lapping operation is time-consuming andaccordingly expensive.

For this'reason it would be advisable to tangentially roll the mainbearing surfaces and the surfaces on the crankpins, because this workwill produce in the least possible time a surface havingthe leastunevenness and having a high carrying capability. However, certainproblems exist in any attempt to carry out this desirable operation,because the known tangential fillet rolling apparatuses do not providefor a reliable prevention of relative movements of the crankshaft blank(workpiece) and the tool rollers in axial direction of the crankshaftblank. Details of the type of prior-art machine which is utilized in thetangential rolling of crankshaft fillets may be found with reference toThe tangential rolling of crankshaft fillets, General Motors EngineeringJournal, Vol. 11, No. 3, 3rd Quarter, 1964. In the known prior-artapparatus which is described there and exemplary of what is known in theart, the crankshaft blank or workpiece is axially fixed againstdisplacement by the inclined fillet rollers which are inclined inmutually opposite directions as seen with: respect to-the longitudinalaxis of the crankshaft blank. This arrangement is quite satisfactoryuntil, in accordance with-the above considerations suggesting that the.surfaces intermediate should also be rolled to avoid a separate lappingoperation, an attempt is made toprovide a cylindrical roller in the sametool unit which utilizes the mutually inclined fillet rollers.

It was found that if this is attempted, there occurs a displacement.between the crankshaft blank and the tool unit in axial direction of thecrankshaft blank, whichcauses portions of the tool unit or supports tomove into engagement with the radial surfaces located at opposite axialends of the cylindrical circumferential surfaces, that is the radialsurfaces into which the fillets merge. It is believed that the reasonfor this difficulty resides in manufacturing tolerances because a verysmall inclination of the axis of the cylindrical roller (used inconjunction with the fillet rollers) with reference to the longitudinalaxis of the crankshaft or the crankpins is sufficient to obtain thenecessary thrust for causing such displacement. However, if suchdisplacement does indeed'occur, the danger exists of substantial damageresulting, especially at the tool unit, because the amount by which suchrelative displacement can occur before contact results with the radialsurfaces mentioned above, is very small.

Evidently, the purposes of the present invention cannot be achieved withthe apparatus known from the prior art under the circumstances outlinedabove.

SUMMARY OF THE INVENTION It is, accordingly, a general object of thepresent invention to overcome the disadvantages set forth above withrespect to the prior art.

More particularly it is an object of the present invention to provide acrankshaft rolling apparatus in which the aforementioned disadvantagesof the prior art are avoided.

A further object of the invention is to provide such a crankshaftrolling apparatus in which the rollers can be utilized for rolling thecircumferential cylindrical surfaces intermediate the fillets, but inwhich relative displacement between tool units and crankshaft blank(workpiece) in axial direction of the latter is reliably avoided.

The apparatus according to the present invention must be capable ofafiording such rolling not only of the circumferential cylindricalsurfaces on the crankpins but also on other portions of the crankshaft,that is the rolling also of the main bearing surfaces.

In pursuance of these and other objects which will still become evident,one feature of the invention resides in a crankshaft rolling apparatushaving a pair of parallel master crankshafts journalled for rotation andhaving respective master portions each having a pair of detail. spacedfillets of predetermined radii of curvature and a circumferentialbearing surface therebetween. A pair of connected lever arms extendtransverse to the master crankshafts and are adapted to support betweenthem under pressure an elongated crankshaft blank in parallelism withthe master crankshafts and having an unfinished portion which alsoincludes a pair of axially spaced fillets and an unfinishedcircumferential bearing surface therebetween. These arms are connectedin motion-receiving relationship with the master crankshafts.

Drive means is provided for rotating the master crankshafts to therebyimpart to the lever arms a reciprocatory motion in an arcuate pathtransverse to the elongation of the master crankshafts.

A first tool unit is provided on one of the arms and includes at leastone rolling tool comprising a pair of conical portions of mutuallyopposite conicity, with these portions being adapted for rollingpressureengagement with the unfinished circumferential bearing surfaceof the unfinished portion of the crankshaft blank. According to theinvention the conical portions of the rolling tool have axial end facesand circumferential surfaces, with the latter merging into the axial endfaces on radii of curvature which are smaller than the aforementionedpredetermined radii by between substantially to percent. A second toolunit is provided on the other arm and includes a counter roll adaptedfor engagement with the circumferential bearing surface of theunfinished portion of the blank, at the side opposite the rolling tool.Pressure exerting means urges the rolling tool and the counter rolltowards one another.

The mutually opposite conicity of the conical portions provides formutually opposite axial thrusts which cancel each other and preventaxial displacement between first tool unit and crankshaft blank. Thus, asmall sliding displacement occurs between the conical portions and thecrankshaft blank,.the displacement being the smaller the smaller theconicity which has been chosen. On the other hand, the conicity must besufficient to afford such axially directed thrust as to counterbalancethe thrust exerted by the other of the conical portions in the oppositedirection, with both axial thrusts of course having to be sufficient toassure that no relative displacement between the conical portions andthe crankshaft can occur, beyond the aforementioned small slidingmovement. The latter is particularly advantageous in terms of theimproved quality obtained thereby for the rolled surface, and the axialcomponent of this small sliding movement combines with the axial thrustresulting from the conicity, with a torque being exerted upon the toolunit which can be absorbed by the journalling of the same.

The smaller radii of curvature at the opposite axial end faces of theconical portions assure that a contact of any portion of the tool unitwith the earliermentioned radial surfaces-and resultant damage-isreliably avoided under all circumstances. All that can occur is that arespective end of a conical portion-the end having a smaller radius ofcurvature than that of the fillet which separates the cylindricalsurface being rolled from the radial surface-will enter into one of thelarger radius fillets; other displacement is then avoided by the radialforce acting upon the rollers and maintaining the same in position inthe respective tool unit so that the only consequence of such anincident will be the tangential rolling of the respective fillet,evidently not a disadvantage.

The conical portions need not be discrete, although they can beconfigurated as discrete rollers of mutually opposite conicity. However,they can also be provided on one and the same roller, as long as thisroller is capable of producing symmetrical oppositely directed axialthrust forces, for instance a roller having a concavely recessedcircumferential surface so that opposite axial end sections of theroller have mutually oppositely directed conicity. A roller of thisconfiguration provides not only the desired advantages as well as therolling of the circumferential cylindrical surface which it contacts,but is capable of giving the circumferential cylindrical surface aslightly outwardly convex contour of controlled configuration if thisshould be desired.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to the construction and method ofoperation thereof, together with additional objects and advantages, willbest be understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front-elevational view ofan apparatus embodying the present invention, with the front cover ofthe apparatus removed to permit a view of the interior;

FIG. 2 is a section, on an enlarged scale, taken on line Il-II of FIG.1;

FIG. 3 is a fragmentary section taken on line III'-III of FIG. 2;

FIG. 4 is a somewhat diagrammatic fragmentary sectional elevationaldetail view illustrating a detail of the invention;

FIG. 5 is a fragmentary elevation illustrating a further embodiment ofthe invention; and

FIG. 6-is a view similar to FIG. 5 but illustrating still anotherembodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before discussing the drawingin detail it is pointed out that the apparatus as shown onlyincorporates the present invention, but is not inherently new. In otherwords, the invention has been illustrated in a basic tangential filletrolling apparatus which is of the type for instance discussed in theearlier-mentioned General Motors publication.

With this in mind and referring now to the embodiment illustrated inFIGS. 1-4, it will be seen that in FIG. 1 there is shown a basictangential fillet rolling apparatus in a front elevational view, withthe front view wall removed to permit a view of the interior. Theapparatus has a motor 4 which drives (refer also to FIG. 2) via belt orother suitable drives 2 and 3 respective master crankshafts 5 and 5. Themaster crankshafts are of exactly the same configuration as thecrankshaft blank (workpiece) which is to be worked and which isidentified with reference numeral ,6. Thus, the master crankshafts 5 and5' have the main bearing surfaces 28, 26' and crankpins 5a and Sa',respectively. The master crankshafts 5 and 5' are journalled in one oftwo connected lever arms, 10, 13, namely in the lever arm as shown inFIG. 2, and when they are rotated by the motor 4, the master crankshafts5 and 5' cause the lever arms 10 and 13 to perform a transverse orreciprocatory motion in an orbital path.

The arm 10 carries a tool unit 11 and the arm 13 carries a tool unit 7,and the crankshaft blank or workpiece 6 is located between the toolunits 7 and 11, extending in axial parallelism with the mastercrankshafts 5 and 5' and being located in the same manner in which theyare positioned, that is each bearing surface for a main bearing and eachbearing surface of a crankpin of the workpiece 6 is associated with andjournalled by one set of the tool units 7 and 11 (although only one setis illustrated because this is considered sufficient for anunderstanding of the invention). The master crankshafts 5 and 5' aredriven in rotation in one and the same direction, being operativelyassociated for this purpose with gears 25, 26 and 27 which cooperatewith one another for this purpose. This means that when the arms 10 and13 move, the workpiece 6 will move in the same sense and if the toolunits 7 and 11 are moved towards one another under pressure, they engagerespective surface portions of the workpiece 6.

The apparatus described thus far is a conventional tangential filletrolling apparatus in which the tools of the tool units 7 and 11 are ofthe type discussed earlier, that is provided with back-up or supportrollers and with fillet-rolling rollers or tool rollers whose axes aremutually inclined with respect to the axial extension of the workpiece6. Thus, in such an apparatus the workpiece 6 is maintained and guidedonly by the tool rollers, no other axial retention or centering devicefor the workpiece 6 being provided. Merely for the sake of completenessit is pointed out that if for instance the workpiece 6 is a crankshafthaving seven bearing surfaces, that is three main bearing surfaces andthe surfaces of a crankpins, the apparatus will have seven of the setsof arms 10 and 13 and seven of the sets of tool units 7 and 11,cooperating with the respective seven bearing surfaces.

Such conventional apparatus cannot, however, be used for rolling thebearing surfaces themselves, for the reasons outlined above; it can beutilized reliably and without danger of damage only for rolling fillets.If it is to be utilized for rolling the bearing surfaces themselves, itmust be provided with the present invention for which purpose the toolunits having the fillet rollers with their mutually inclined axes areremoved and replaced with tool units 7 and 11 according to the presentinvention.

Reference should now be had to FIGS. 2-4 in partic' ular which show theinvention in defail. The tool unit 7 is provided with a rolling tool inform of two discrete tool rollers or portions 8 and 9 which are locatedat opposite lateral sides of the axis of the workpiece 6 and which areof mutually opposite conicity (see FIG. 3). The rollers 8 and 9 contactthe cylindrical surface which they are to treat on the workpiece 6, andare supported by the support ro back-up rollers 15 or 16 on the one handand 17 and 18 on the other hand. The tool unit 11 is provided with acounter roller 12 which is supported against the surface of theworkpiece 6 on the one hand and against the back-up rollers 19 and 20 onthe other hand.

As the drawingshows, the tool unit 11 is connected to the arm 10,whereas the tool unit 7 is connected to the arm 13. The two arms areconnected with one another by the pivot 14 and can be moved about thispivot with reference to one another by the hydraulic cylinder and pistonunit 29 which requires no detailed description.

As more particularly shown in FIG. 3, the rollers 8 and 9 are ofmutually opposite conicity, having identical cone angles and thusexerting upon the workpiece 6-whose surface they contact as also shownin FIG. 3- equal axial thrust, with the direction of thrust of theroller 8 being opposite to the direction of thrust exerted by the roller9. Thus, the thrust forces exerted by the rollers 8 and 9 will cancel ineach other and are in equilibrium.

As already pointed out before, a pair of arms 10, 13 and tool units 7and 11 is provided to cooperate with each bearing surface (for instanceseven or more) of the workpiece 6. Because the workpiece 6 is completelyloose in so far as its retention against axial movement is concerned, itis necessary that the rollers of the tool units 7 and 11 not cause it toshift in axial direction. However, to prevent the possibility of damagein the event such movement should nevertheless occur, the presentinvention provides for the radius r of curvature at the opposite axialends of the respective rollers 8 and 9 to be smaller by substantially 20and 30 percent than the corresponding radius at the fillets of themaster crankshaft, and thereby of the fillets on the workpiece 6 whichare configurated in exact correspondence with those of the mastercrankshaft. FIG. 4 explains this most clearly. In FIG. 4 there isillustrated fragmentarily and in section a roller 8 having thecircumferential surface 8a and the opposite axial end faces 8b. Theradius r where the end faces 8b merge into the circumferential surface8a should be compared with the fillet radius r+ 20-30 percent on whichthe cylindrical circumferential surface 51 of the portion of one of themaster crankshafts 5 (the same is of course true also of the mastercrankshaft 5') merges into the two radial surfaces 52 located atopposite axial ends of the circumferential surfaces 51. The surfaces 51and 52 correspond precisely to the similar surfaces provided on theworkpiece 6, except that as mentioned before the radius r of the rollers8 and 9 is smaller by 20-30 percent than the radius r 20-30 percent onthe fillets of the master crankshafts 5 and 5'. It is evident that underthese circumstances damage to the surfaces 52 is impossible even if theroller 8 should move as close as is possible in axial direction towardsone of the surfaces 52, because all that will happen is that it willmove into one of the fillets on the workpiece, corresponding to thoseshown on the master crankshaft in F IG. 4, and compact the material inthe fillet without any portion of the roller 8 ever having a possibilityof coming into contact and doing damage to the surfaces 52. Therelationship of radius r on the rollers 8 and 9 with respect to theradius r 20-30 percent of the fillets has been found to be highlyadvantageous because it assures that no damage can occur to the surfaces52.

In FIG. 5 l have illustrated an embodiment of the invention where only aportion of the workpiece 6 is shown, but wherein the conical contour ofthe rollers 8' and 9' is somewhat different from that of the rollers 8and 9. In other respects this embodiment corresponds to the onediscussed previously, and it should be noted that the radius 30 of thefillet on the workpiece 6 is larger (again by substantially 20-30percent) than the radius 31 on the rollers 8' and 9, respectively.

The embodiment in FIG. 6, finally, again shows the workpiece 6. Here,however, the rolling tool which in the preceding embodiments was in formof tool rollers 8 and 9, or 8' and 9, respectively, is configurated as asingle roller 21 having its circumferential surfaces concavely recessedas illustrated. Thus, the opposite axial portions of the roller 21 havemutually opposite conicity to achieve the oppositely directedsymmetrical axial thrust forces. On the other hand, the opposite axialend faces of the roller 21 again merge into the circumferential surfacethereof on radii which are smaller by substantially 2030 percent thanthe radii of the fillets on the workpiece 6, in keeping with thepreceding embodiments. The roller 21 is engaged and urged against thesurface of the workpiece 6 by a counter roller 22 of convex contour soas to matingly engage the concavity in the roller 21. If anyunevennesses in the surface being treated by the roller 1 should resultfrom the previous rolling of the fillets, then these would be smoothedout by the action of the roller 21 but the surface on the workpiece 6would be given a slightly convex contour which may be desirable in somecircumstances, because for instance it will aid in the axial guidance ofthe workpiece 6 in an engine assembly as well as preventing edgepressures in the bearing when the workpiece 6 is installed.

Thus, it will be seen that by a simple substitution of the rollers 8, 9or 8, 9', or 21, according to the present invention (these rollers mayof course already be installed in a complete tool unit with theircooperating counter or back-up rollers) in a tangential fillet rollingmachine in place of the tool rollers which are used for rolling thefillets themselves, it has become possible to reliably, accurately andspeedily roll the cylindrical bearing surface intermediate therespective fillets, utilizing the same tangential fillet rollingapparatus as before, and thus achieving significant economies not onlyin terms of operation but also in terms of investments, while furtherachieving a reliable protection against damage to the surface 52 and/orany portions of the respective tool units.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in acrankshaft rolling apparatus, it is not intended to be limited to thedetails shown, since various modifications and structural changes may bemade without departing in any way from the spirit of the presentinvention.

Without further analysis the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting features thatfrom the standpoint of prior art fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent isset forth in the appended 1. In a crankshaft rolling apparatus, incombination, a pair of parallel master crankshafts joumalled forrotation and having respective master portions each having a pair ofaxially spaced fillets of predetermined radii of curvature and acircumferential bearing surface therebetween; a pair of connected leverarms extending transverse to said master crankshafts and adapted tosupport between them under pressure an elongated crankshaft blank inparallelism with said master crankshafts and having an unfinishedportion also including a pair of axially spaced fillets and anunfinished circumferential bearing surface therebetween, said arms beingconnected in motion-receiving relationship with said master crankshafts;drive means for rotating said master crankshafts and for therebyimparting to said lever arms a reciprocatory motion in an arcuate pathtransverse to the elongation of said master crankshafts; a first toolunit provided on one of said arms and including at least one rollingtool which comprises a pair of conical portions of mutually oppositeconicity, said portions being adapted for rolling pressure-engagementwith said unfinished circumferential bearing surface of said unfinishedportion and having axial end faces and circumferential surfaces whichmerge into said axial end faces on radii of curvature which are smallerthan said predetermined radii by between substantially 20-30 percent; asecond tool unit on the other of said arms and including a counter rolladapted for engagement with said unfinished circumferential bearingsurface of said unfinished portion at a side opposite said rolling tool;and pressure-exerting means for urging said rolling tool and saidcounter roll towards one another.

2. In an apparatus as defined in claim 1, wherein said conical portionsof said rolling tool are discrete roller elements.

3. In an apparatus as defined in claim 2, wherein said roller elementshave axes of rotation which extend in direction longitudinally of thecrankshaft blank when the same is supported between said arms.

4. In an apparatus as defined in claim 1, wherein said rolling tool is aone-piece roller element, and wherein said conical portions are providedon the respective axial halves of said roller element.

5. In an apparatus as defined in claim 4, wherein said roller elementhas a circumferential surface surrounding an axis of rotation of saidroller element and being concavely curved inwardly towards said axisintermediate the opposite axial ends of said roller element.

6. In an apparatus as defined in claim 5, wherein said first tool unitfurther comprises at least one back-up roller having a convexly curvedcircumferential surface and supportingly engaging said concavely curvedsurface of said roller element.

7. In an apparatus as defined in claim 1, said first tool unit furthercomprising back-up roller means in contact with and contoured formatingly engaging said conical portions.

8. In an apparatus as defined in claim 1, said crankshaft blank having alongitudinal axis; and wherein said conical portions are adapted to belocated at opposite lateral sides of said longitudinal axis.

9. In an apparatus as defined in claim 1; further comprising connectingmeans connecting said arms for pivoting movement towards and away fromone another; and force-exerting means for drawing said arms towards oneanother so as to exert pressure upon a crankshaft blank supportedbetween them.

10. In a crankshaft rolling apparatus wherein an elongated workpiecehaving an unfinished portion provided with a pair of axially spacedfillets and an unfinished circumferential bearing surface therebetweenis held under pressure between two arms which are caused to reciprocatein unison in an arcuate path transverse to the elongation of saidworkpiece by transmission of motion from two parallel rotating mastercrankshafts having respective master portions each having a pair ofaxially spaced fillets of predetermined radii of curvature and arespective master bearing surface therebetween, in combination, a firsttool unit provided on one of said arms and including at least onerolling tool adapted for rolling pressure engagement with saidunfinished bearing surface of said unfinished portion and comprising apair of conical portions of mutually opposite conicity having axial endfaces and circumferential surfaces which merge into said axial end faceson radii of curvature which are smaller than said predetermined radii bysubstantially 20-30 percent; and a second tool unit provided on theother of said arms and including a counter roller adapted for rollingpressure engagement with said unfinished bearing surface of saidunfinished portion at a side thereof which is opposite said rollingtool.

1. In a crankshaft rolling apparatus, in combination, a pair of parallelmaster crankshafts journalled for rotation and having respective masterportions each having a pair of axially spaced fillets of predeterminedradii of curvature and a circumferential bearing surface therebetween; apair of connected lever arms extending transverse to said mastercrankshafts and adapted to support between them under pressure anelongated crankshaft blank in parallelism with said master crankshaftsand having an unfinished portion also including a pair of axially spacedfillets and an unfinished circumferential bearing surface therebetween,said arms being connected in motion-receiving relationship with saidmaster crankshafts; drive means for rotating said master crankshafts andfor thereby imparting to said lever arms a reciprocatory motion in anarcuate path transverse to the elongation of said master crankshafts; afirst tool unit provided on one of said arms and including at least onerolling toOl which comprises a pair of conical portions of mutuallyopposite conicity, said portions being adapted for rollingpressure-engagement with said unfinished circumferential bearing surfaceof said unfinished portion and having axial end faces andcircumferential surfaces which merge into said axial end faces on radiiof curvature which are smaller than said predetermined radii by betweensubstantially 20-30 percent; a second tool unit on the other of saidarms and including a counter roll adapted for engagement with saidunfinished circumferential bearing surface of said unfinished portion ata side opposite said rolling tool; and pressure-exerting means forurging said rolling tool and said counter roll towards one another. 2.In an apparatus as defined in claim 1, wherein said conical portions ofsaid rolling tool are discrete roller elements.
 3. In an apparatus asdefined in claim 2, wherein said roller elements have axes of rotationwhich extend in direction longitudinally of the crankshaft blank whenthe same is supported between said arms.
 4. In an apparatus as definedin claim 1, wherein said rolling tool is a one-piece roller element, andwherein said conical portions are provided on the respective axialhalves of said roller element.
 5. In an apparatus as defined in claim 4,wherein said roller element has a circumferential surface surrounding anaxis of rotation of said roller element and being concavely curvedinwardly towards said axis intermediate the opposite axial ends of saidroller element.
 6. In an apparatus as defined in claim 5, wherein saidfirst tool unit further comprises at least one back-up roller having aconvexly curved circumferential surface and supportingly engaging saidconcavely curved surface of said roller element.
 7. In an apparatus asdefined in claim 1, said first tool unit further comprising back-uproller means in contact with and contoured for matingly engaging saidconical portions.
 8. In an apparatus as defined in claim 1, saidcrankshaft blank having a longitudinal axis; and wherein said conicalportions are adapted to be located at opposite lateral sides of saidlongitudinal axis.
 9. In an apparatus as defined in claim 1; furthercomprising connecting means connecting said arms for pivoting movementtowards and away from one another; and force-exerting means for drawingsaid arms towards one another so as to exert pressure upon a crankshaftblank supported between them.
 10. In a crankshaft rolling apparatuswherein an elongated workpiece having an unfinished portion providedwith a pair of axially spaced fillets and an unfinished circumferentialbearing surface therebetween is held under pressure between two armswhich are caused to reciprocate in unison in an arcuate path transverseto the elongation of said workpiece by transmission of motion from twoparallel rotating master crankshafts having respective master portionseach having a pair of axially spaced fillets of predetermined radii ofcurvature and a respective master bearing surface therebetween, incombination, a first tool unit provided on one of said arms andincluding at least one rolling tool adapted for rolling pressureengagement with said unfinished bearing surface of said unfinishedportion and comprising a pair of conical portions of mutually oppositeconicity having axial end faces and circumferential surfaces which mergeinto said axial end faces on radii of curvature which are smaller thansaid predetermined radii by substantially 20-30 percent; and a secondtool unit provided on the other of said arms and including a counterroller adapted for rolling pressure engagement with said unfinishedbearing surface of said unfinished portion at a side thereof which isopposite said rolling tool.